Oriented Nano-Structure (“ONS”) optical media provide storage capacities/densities which are increased by a factor as high as about 5, relative to the currently available CD, DVD, HD-DVD, etc., media. Advantageously, such ONS media and systems are backward compatible with the CD, DVD, HD-DVD technologies, and suitable for use in new markets for small form-factor discs such as are currently employed in personal audio/video devices, e.g., Game Boys®, iPODS®, etc.
Referring to FIG. 1, the upper illustration is a plan view of a data track (or recording cell) of a conventionally encoded optical medium, showing a pattern comprised of a plurality of elongated pits (dark areas) formed in the surface of the medium and the corresponding output pattern of a read head or photodetector which is produced by the pattern of pits, wherein tmin indicates the minimum spacing between adjacent pits, which limits the maximum data encoding density and reading rate for a given disc rotation speed.
Still referring to FIG. 1, the lower illustration shows the output pattern of a read head or photodetector of a multi-states encoded medium, wherein the surface of the medium includes a data track (or recording cell) with a pattern of pits configured as multilevel oriented nano-structures. As is evident from a comparison of these illustrations, and noting that t<tmin, the areal recording density and data rate are significantly increased (i.e., ≧5×) in the multi-states encoded medium by packing more information (i.e., M states) into the recording cell, while advantageously allowing operation with far-field optics similar to those of conventional optical drives.
Adverting to FIG. 2, shown therein are cross-sectional system views and plan views of the encoded surfaces of conventional CD, DVD, Blu-Ray®, and ONS media, along with associated performance characteristics and operating parameters of these media types. As before, it is evident that ONS media offer significantly increased areal recording density and data rate vis-à-vis the earlier generations of optical media by virtue of: (1) decreased spacing between adjacent data tracks; (2) the ability to widely vary the angles of the pit walls, hence the encoding information; and (3) the increased pit density along each data track.
Currently, however, ONS technology is limited to read-only memory (ROM) devices produced via stamping techniques. ONS technology possesses the potential for becoming significantly more valuable if disc media were available in “write once” and/or “re-writable” versions. Such writable ONS discs could be expected to attain data storage capacities in the 150-1,000 Gbyte range when in a 5.25 in. diameter format and could be used equally well for content delivery (as in the current CD and DVD markets) and archival storage and retrieval applications.
Accordingly, there exists a clear need for means and methodology for means and methodology for optical writing of multilevel oriented nano-structures in the surfaces of discs utilized as optical data/information storage and retrieval media. Further, their exists a clear need for the development and use of writable optical ONS media with ultra-high data storage capacities in excess of about 150 Gbytes for disc diameters comparable to those of currently available CD and DVD media.